Ladder



p 0, 1935. J. M. LITHGOW 2,014,141

LADDER Filed Nov, 21, 1934 INVENTOR m a, 21% K 6% MW/M ATTORNEYS mentary View in front Patented Sept. 10, 1935 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to a ladder equipped with a tang, whereby the erected ladder may stand more secure.

In the accompanying drawing, Fig. I is a fragelevation, and Fig. II a fragmentary View in side elevation, of a ladder embodying the invention. Fig. III is a view to larger scale and in vertical section, on the plane indicated by the line III-III, Fig. I, showing the basal portion of one of the longitudinal members of such a ladder as that shown in Figs. I and II. Figs. IV and V are views in perspective of a keeper and a block, which, being assembled with the longitudinal member of a ladder, constitute an embodiment of the invention.

A block I is provided of triangular outline, and, advantageously, of the isosceles triangular outline best shown in Fig. III, and of the prismatic form best shown in Fig. V. The block is advantageously of such proportions and size as to present to the square-cut end of the longitudinal member 2 of the ladder a base substantially coextensive with that square-cut end. This will appear on consideration of Figs. I, II, and III. The keeper consists of a belt portion 3, adapted substantially to surround the block I adjacent its upper, basal end; and to constitute in the assembly a retaining member, from whose lower, open end the apex of the triangular block protrudes. This also is indicated in Figs. I, II, and III. The keeper includes also an integral strap 4, by which it may be secured to the longitudinal member 2 of the ladder. To such end, in the embodiment shown, the strap is provided with bolt holes through which, and through the longitudinal member 2, securing bolts 5 extend.

The keeper will ordinarily be formed of sheet steel, suitably cut, shaped, and welded. The block I is an integrated block of suitable, hard abrasive particles, held in a matrix. It may, for example, advantageously be formed of that artificial breccia including granules of carbon silicide that is applied to various uses, such, for example, as grinding wheels, and is commonly termed carborundum.

In the assembly it will be perceived that the block presents to the square end of the longitudinal member of the ladder an extended surface of abutment, and it presents to the surface upon which the ladder may be erected a single peak--a knife edge. It will be particularly remarked that the attaching means-in this case the bolts 5--do not sustain the weight of a climber upon the erected ladder, but that the weight of the ladder and the climber who may be upon it is sustained. directly and immediately by the block I. The block I has extended bearing with the square-cut end of the longitudinal member, and has a con- 5 centrated peak or knife-edge bearing upon the surface upon which the ladder is erected. Ladders are employed in all sorts of places-on construction jobs, at fires, by cleaners, on shipboard, and on land, and have to stand on supporting 10 surfaces that afford varying degrees of security.

It is a simple matter to get firm footing in earth for an inclined ladder, but it is a very different matter to get firm footing upon a smooth floor or pavement, or upon a steel deck-plate, particu- 15 larly if the surface be coated with grease. It is to meet such exacting conditions as those suggested that this invention has been directed. It is by virtue of the hardness of the block I, and the sharpness of its component grains, that it has 20 the capacity, under load, of biting into even such surfaces as those indicated, and of affording security and affording safety to life and limb of the user.

The drawing shows the invention applied to the 25 two longitudinal members of an ordinary ladder. For particular services, ladders including a single longitudinal member are employed. To such a ladder, and, generally, to all ladders that include a longitudinal member or members, this invention 30 is manifestly applicable. 1

I claim as my invention:

1. A ladder including a longitudinal member equipped with a tang in the form of a prismatic block of breccia including granular abrasive, one 35 face of the block abutting upon the end of the longitudinal member and one edge presenting a single knife-edge to a supporting surface.

2. A ladder including a longitudinal member equipped with a tang in the form of a triangular 40 prismatic block applicable to the longitudinal member in position with either of its three prism faces in abutment thereon, and a keeper bolted to the said longitudinal member and including a pocket of triangular prismatic form corresponding to the form of the block, but truncated and open throughout the extent of the bases of the truncated prism, whereby the block may be removably secured to the longitudinal ladder member with any one of its prismatic edges protruding from the keeper.

JOHN M. LITHGOW. 

